Influence of Adjacent and Border Crops on the Incidence of Fall Armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in Maize

Abstract

Background: Maize is one of the predominant millets cultivated in an area of 6500 ha both under drip and open irrigation systems in Dharmapuri district. The infestation of invasive insect pest Spodoptera frugiperda poses major threat to maize cultivation and increased the cost towards plant protection since 2018. In the integrated pest management strategies, the benefits of growing border and inter crop has been studied in detail but least emphasis was given to the crops grown in adjacent fields to the main crop. The cropping pattern in Dharmapuri district is highly diversified and the farmers prefer to grow more number of crops across the seasons compared to other maize growing areas. Methods: The present survey envisages the influence of adjacent and border crops on the incidence of fall armyworm in maize. The field incidence of fall armyworm in maize crop surrounded by other crops such as tapioca, nerium, cotton and maize fields with blackgram, cowpea and sesame as border crops were studied during kharif season of 2018 and 2019. Result: The maize fields surrounded by tapioca and nerium crop recorded lower fall armyworm incidence (3.00 - 10.00%) followed by field surrounded by tapioca on either side of maize (4.50 - 14.50%) during 15 to 60 days after emergence. Growing of border crops such as blackgram, sesame and cowpea recorded 24.50, 23.50 and 16.50% incidence at 60 DAE, respectively. With regard to grain yield, no marked variation was observed in different crop combination. The higher return (Rs. 86040/ha) and benefit cost ratio (2.65) was observed in maize crop adjacent to tapioca and nerium crop. The lower net return (Rs. 75360/ha) and benefit cost ratio (2.36) was realized in maize crop adjacent to maize crop. In most of the management strategies pulses have been inducted either border or intercrop to attract natural enemies and thwart the host insects. In the present survey, tapioca and nerium crop combination reduces the fall armyworm incidence. Hence tapioca and nerium crop combinations can be tried as border crop to push the fall armyworm away from the maize crop. The days required for advanced planting and crop combinations should be studied in detail to devise effective fall armyworm management strategies.